The present invention relates to the mixing of fluid dispersions and more specifically to apparatus and methods for mixing a tinting concentrate disposed in a container.
In retail paint stores, architectural paints are typically prepared by adding one or more tinting concentrates to a white or pastel base to obtain a particular color desired by a customer. A tinting concentrate comprises highly concentrated levels of color pigment ground or dispersed into a grinding vehicle, such as a blend of water, surfactants, dispersants and other additives. One representative tinting concentrate blend could comprise one or more pigments, water, surfactants, dispersants and ethylene glycol. Tinting concentrates are typically provided in plastic containers commonly referred to as F-style containers. An F-style container generally has a rectangular body with a top mounted handle and an offset pour spout. Examples of F-style containers are shown in U.S. Pat. Nos. Des. 228,230; Des. 237,255; and Des. 274,130, all of which are hereby incorporated by reference.
Since a tinting concentrate is a dispersion of solid pigment in a liquid vehicle, the pigment tends to settle toward the bottom of the F-style container through the force of gravity. If such settling is allowed to occur, the concentration of pigment in the tinting concentrate will vary from location to location within the F-style container. Such variations in the pigment concentration can cause inaccuracies in tinting and can adversely impact the dispersion of the pigment in the paint.
In order to prevent the pigment from settling in a tinting concentrate, the tinting concentrate is mixed by manually shaking the F-style container. Such manual shaking, however, is physically demanding and often results in less than satisfactory mixing of the tinting concentrate. Accordingly, it would be desirable to mix the tinting concentrate using a mixing machine.
Mixing machines exist for mixing paint in containers. Conventional paint mixing machines, however, are specially designed to handle metal cylindrical one gallon paint cans and/or five gallon cylindrical plastic buckets. Conventional mixing machines typically cannot accommodate F-style containers or will damage F-style containers.
Accordingly, there is a need in the art for an apparatus and method for mechanically mixing tinting concentrates. The present invention is directed to such an apparatus and method.